Motorized garage door operators and the like have been developed of a type which utilize mechanical limit switches for controlling the operator motor when the door reaches open and closed limit positions, respectively. Typical door operators with mechanical snap-action type switches have been developed wherein the switches are mounted on a frame of the operator and in proximity to a rotating threaded shaft with one or more linearly traveling nut-like members mounted thereon which engage and actuate the limit switches when the door is traveling between open and closed positions. At least two mechanical type switches are generally required, a first switch for effecting control of the operator motor to shut off when the door reaches a full down or closed position and a second switch to effect motor shut off when the door reaches a full up or open position. Typically, in prior art operators, the first switch is provided with multiple sets of electrical contacts or a third mechanical limit switch is used to sense the door position just prior to the fully closed condition to disable obstruction sensing devices mounted on the lower edge of the door to prevent such devices from reversing door movement just prior to the door reaching its fully closed position.
Although mechanical limit switches are widely used they hold certain disadvantages, including lack of reliability, physical size and the need to provide hardwiring to and from the switches. However, in accordance with the present invention the disadvantages of mechanical limit switches are overcome by providing a door operator controller including so called optical limit switches.